Oscillatory Reconnection of a 2D X-point in a hot coronal plasma

TL;DR

This study explores oscillatory magnetic reconnection in a hot coronal plasma, revealing how thermal conduction influences its behavior and suggesting its potential use in solar seismology.

Contribution

It is the first to analyze oscillatory reconnection at coronal temperatures, incorporating anisotropic thermal conduction into the MHD model.

Findings

Thermal conduction simplifies the oscillation spectrum.

Thermal conduction increases the decay rate of oscillations.

A relationship between magnetic field strength, decay rate, and period was identified.

Abstract

Oscillatory reconnection (a relaxation mechanism with periodic changes in connectivity) has been proposed as a potential physical mechanism underpinning several periodic phenomena in the solar atmosphere including, but not limited to, quasi-periodic pulsations (QPPs). Despite its importance, however, the mechanism has never been studied within a hot, coronal plasma. We investigate oscillatory reconnection in a one million Kelvin plasma by solving the fully-compressive, resistive MHD equations for a 2D magnetic X-point under coronal conditions using the PLUTO code. We report on the resulting oscillatory reconnection including its periodicity and decay rate. We observe a more complicated oscillating profile for the current density compared to that found for a cold plasma, due to mode-conversion at the equipartition layer. We also consider, for the first time, the effect of adding anisotropic thermal conduction to the oscillatory reconnection mechanism, and we find this simplifies the spectrum of the oscillation profile and increases the decay rate. Crucially, the addition of thermal conduction does not prevent the oscillatory reconnection mechanism from manifesting. Finally, we reveal a relationship between the equilibrium magnetic field strength, decay rate, and period of oscillatory reconnection, which opens the tantalising possibility of utilizing oscillatory reconnection as a seismological tool.